Biased angle polyaxial pedicle screw assembly

ABSTRACT

A pedicle screw assembly and method of assembly comprises a longitudinal member; a screw head comprising a bulbous end, wherein the screw head has a slot adapted to receive the longitudinal member; a bone fixator component comprising a concave socket having a biased angled top and a rounded bottom adapted to receive the screw head; a locking pin adapted to engage the screw head, the bone fixator component, and the longitudinal member; and a blocker adapted to engage the screw head and to secure the longitudinal member. Additionally, the bone fixator component may be configured as any of a bone screw and a hook.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 60/548,543 filed on Feb. 27, 2004 and U.S. ProvisionalPatent Application No. 60/622,454 filed on Oct. 27, 2004, the contentsof which in their entireties are herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The embodiments of the invention generally relate to medical devices andassemblies, and more particularly to an orthopedic surgical implantassembly used in the field of surgical lumbar, thoracic, and cervicalspine treatment.

2. Description of the Related Art

Surgical procedures treating spinal injuries are one of the most complexand challenging surgeries for both the patient and the surgeon. Whenthere are various deformities, trauma, or fractures of the vertebra,surgeons may attempt to “fuse” them together by attaching screw-likedevices into the pedicles of the spine and thereby connecting severalvertebrae (typically two or more) using a semi-rigid rod. However, dueto the complexity of the human anatomy, most surgeons must bend the rod(causing notches thereby reducing fatigue resistance) before placingthem into two or more non-aligned pedicle screws that vary in height inorder to properly stabilize the pedicle screw assembly within thepatient's body. However, this bending causes notches and reduces fatigueresistance and wastes valuable surgery time before the surgeon is ableto insert the rod. That is, the surgeon must sacrifice the freedom ofoptimal screw placement in the spine for ease of construct assembly.

Most conventional polyaxial screw systems generally consist of a bonescrew with the top portion of that screw pivoting inside a screw head.This typical conventional design necessitates the bones screw to have anarrow neck just below the entrance to the bottom of the screw head.This allows clearance for the polyaxiality motion of the screwconstruct. However, this smaller and weaker neck portion issignificantly further away from the forces being applied through therod, which consequently allows a bigger moment arm and increases thechance of screw breakage at the weak neck portion.

Depending on the purpose of the spine surgery, indications, and patientsize, surgeons must pre-operatively choose between different spinalsystems with differing rod sizes pre-operatively sometimes causingdelays in surgery while waiting for more adequate systems to besterilized. Most conventional systems depend on deformation and notchingof the rod to be able to lock it into the screw head. This tends tosignificantly reduce the fatigue life of the rod. Some surgeons prefermonoaxial screws for rigidity, while some sacrifice rigidity forsurgical flexibility in screw placement. Therefore, a system is neededto accommodate both theories. For example, during scoliosis surgeryconventional polyaxial systems typically cannot lock into a desiredposition to persuade the spinal column into the desired correctionbefore final construct assembly.

Most conventional top loading polyaxial spine screws address cantileverfailure by utilizing too much stress to the constructs making themweaker in other areas of concern. Moreover, most conventional polyaxialscrews do not generally offer enough medial/lateral flexibility becausethe rod sits too closely on top of the center of rotation of the bonescrew producing a smaller arc of rotation. Furthermore, mostconventional titanium top loading screw systems only accommodate one rodsize. Additionally, most conventional spinal implant designs can onlyaccommodate either a monoaxial design or, separately, a polyaxialdesign, but not in one assembly. As such, most conventional screwassemblies cannot accommodate 3, 3.25, 3.5, and 4 mm rod sizes in onesingular screw assembly. Typically, the particular size of rod useddepends on the patient's size and other factors, which may not bedetermined until after the surgery begins and, potentially, only afterthe surgeon has already inserted the bone screw into the bone.

Generally, most conventional top loading polyaxial spine screws do notdo enough to address cantilever failure of the assembly components.Additionally, most polyaxial screws generally do not offer enoughflexibility because the rod sits too closely on top of the center ofrotation of the bone screw producing a smaller arc of rotation.Furthermore, most conventional top loading screw systems generally donot accommodate different rod sizes. Moreover, most conventionalpolyaxial screws offer an equal degree of rotation or freedom referencedto the main screw axis. However, some portions of the spine do not needthe system to provide equal polyaxial motion in all directions. Forexample, some portions of the spine require a range of 5 degrees in onedirection and 45 degrees in the opposite direction on the same plane.Generally, most conventional systems simply provide 25 degrees allaround. Thus, there remains a need for a new and improved pedicle screwassembly capable of overcoming the limitations of the conventionaldesigns thereby providing the surgeon with improved intra-operativeflexibility and the patient with an improved prognosis for better andcomplete rehabilitation.

SUMMARY OF THE INVENTION

In view of the foregoing, an embodiment of the invention provides apedicle screw assembly comprising a screw head comprising a bulbous end;a bone fixator component comprising an angled concave socket adapted toreceive the bulbous end of the screw head; a pin mounted in the screwhead; and a blocker adapted to engage the screw head. The screw headcomprises a slot adapted to receive a longitudinal member. Moreover, theconcave socket of the bone fixator component comprises an angled top anda rounded bottom. Preferably, the concave socket of the bone fixatorcomponent comprises an inner portion adapted to receive the bulbous endof the screw head; and a dimpled outer portion.

Additionally, the pin is preferably adapted to engage the bone fixatorcomponent and the longitudinal member, and the blocker is preferablyadapted to secure the longitudinal member. Preferably, the pin comprisesan upper saddle portion having a slot and a pair of upright ends; and alower tapered portion adjacent to the slot. Preferably, the screw headfurther comprises two opposed upright ends separated by the slot,wherein each of the opposed upright ends comprise an inner wall and anouter wall, wherein the inner wall comprises wall threads, and whereinthe outer wall comprises grooves.

Additionally, the blocker preferably comprises blocker threadsconfigured around an outer perimeter of the blocker, the blocker threadsbeing dimensioned and configured to mate with the wall threads.Furthermore, the bulbous end of the screw head may comprise a pluralityof slots terminating at an opening at a tip of the bulbous end. Also,the bulbous end of the screw head preferably comprises a hole configuredto receive the pin. Moreover, the bone fixator component may compriseany of a bone screw and a hook configuration.

Another aspect of the invention provides a pedicle screw assemblycomprising a longitudinal member; a screw head comprising a bulbous end,wherein the screw head has a slot adapted to receive the longitudinalmember; a bone fixator component comprising a concave socket having abiased angled top and a rounded bottom adapted to receive the screwhead; a locking pin adapted to engage the screw head, the bone fixatorcomponent, and the longitudinal member; and a blocker adapted to engagethe screw head and to secure the longitudinal member, wherein theconcave socket of the bone fixator component preferably comprises aninner portion adapted to receive the bulbous end of the screw head; anda dimpled outer portion. Furthermore, the locking pin preferablycomprises an upper saddle portion having a slot and a pair of uprightends; and a lower tapered portion adjacent to the slot. Moreover, thebulbous end of the screw head preferably comprises a hole configured toreceive the pin. Additionally, the bone fixator component may compriseany of a bone screw and a hook configuration.

Another embodiment of the invention provides a method of assembling apedicle screw assembly, wherein the method comprises attaching a screwhead comprising a bulbous end to a bone fixator component, wherein thebone fixator component comprises an angled concave socket adapted toreceive the bulbous end of the screw head; securing the bone fixatorcomponent in a bone; securing a locking pin in the screw head; engagingthe saddle pin with the bone fixator component; inserting a longitudinalmember in the screw head; and inserting a blocker in the screw head,wherein engagement of the blocker with the screw head causes expansionof the bulbous end of the screw head in the angled concave socket of thebone fixator component.

The embodiments of the invention offer a surgeon more lateral correctivedistance than conventional screw assemblies and can accommodate thecervical spine anatomy with a biased angle. The embodiments of theinvention may be used as a fixation device in the posteriorcervical-thoracic spine.

Additionally, the embodiments of the invention provide an improvement inthe field of surgical lumbar and thoracic and cervical spine treatment.The assembly provided by the embodiments of the invention may also beused anteriorly or posteriorly. Furthermore, the assembly provided bythe embodiments of the invention may be utilized in surgeries to achieveanterior lumbar interbody fusion, posterior lumbar interbody fusion,transverse lumbar interbody fusion, degenerative disc disease, adult andpediatric scoliosis as a fixation device, and posterior cervical fusion.

These and other aspects of the embodiments of the invention will bebetter appreciated and understood when considered in conjunction withthe following description and the accompanying drawings. It should beunderstood, however, that the following descriptions, while indicatingpreferred embodiments of the invention and numerous specific detailsthereof, are given by way of illustration and not of limitation. Manychanges and modifications may be made within the scope of theembodiments of the invention without departing from the spirit thereof,and the embodiments of the invention include all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the invention will be better understood from thefollowing detailed description with reference to the drawings, in which:

FIG. 1 illustrates an exploded view of the screw assembly according toan embodiment of the invention;

FIG. 2(A) illustrates a perspective view of the bone fixator componentof FIG. 1 according to an embodiment of the invention;

FIG. 2(B) illustrates a front view of the bone fixator component of FIG.2(A) according to an embodiment of the invention;

FIG. 2(C) illustrates a cross-sectional top view cut along section X-Xof the bone fixator component of FIG. 2(B) according to an embodiment ofthe invention;

FIG. 2(D) illustrates a cross-sectional side view cut along section A-Aof the bone fixator component of FIG. 2(B) according to an embodiment ofthe invention;

FIG. 3(A) illustrates a perspective view of the screw head of FIG. 1according to an embodiment of the invention;

FIG. 3(B) illustrates a front view of the screw head of FIG. 3(A)according to an embodiment of the invention;

FIG. 3(C) illustrates a bottom view of the screw head of FIG. 3(A)according to an embodiment of the invention;

FIG. 3(D) illustrates a cross-sectional side view cut along section C-Cof the screw head of FIG. 3(B) according to an embodiment of theinvention;

FIG. 4(A) illustrates a perspective view of the saddle pin of FIG. 1according to an embodiment of the invention;

FIG. 4(B) illustrates a side view of the saddle pin of FIG. 4(A)according to an embodiment of the invention;

FIG. 4(C) illustrates a bottom view of the saddle pin of FIG. 4(A)according to an embodiment of the invention;

FIG. 4(D) illustrates a top view of the saddle pin of FIG. 4(A)according to an embodiment of the invention;

FIG. 4(E) illustrates a front view of the saddle pin of FIG. 4(A)according to an embodiment of the invention;

FIG. 5(A) illustrates a perspective view of the blocker of FIG. 1according to an embodiment of the invention;

FIG. 5(B) illustrates a cross-sectional side view of the blocker of FIG.5(A) according to an embodiment of the invention;

FIGS. 6(A) through 6(D) illustrate several views of a fully engagedscrew assembly according to an embodiment of the invention;

FIGS. 7(A) through 7(B) illustrate several views of a fully engagedscrew assembly in various stages of angulation according to anembodiment of the invention;

FIGS. 8(A) through 8(E) illustrate several cross-sectional views of ascrew assembly in various stages of assembly according to an embodimentof the invention;

FIGS. 9(A) through 9(D) illustrate several cross-sectional views of ascrew assembly in various stages of engagement according to anembodiment of the invention; and

FIG. 10 is a flow diagram illustrating a preferred method according toan embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The embodiments of the invention and the various features andadvantageous details thereof are explained more fully with reference tothe non-limiting embodiments that are illustrated in the accompanyingdrawings and detailed in the following description. It should be notedthat the features illustrated in the drawings are not necessarily drawnto scale. Descriptions of well-known components and processingtechniques are omitted so as to not unnecessarily obscure theembodiments of the invention. The examples used herein are intendedmerely to facilitate an understanding of ways in which the embodimentsof the invention may be practiced and to further enable those of skillin the art to practice the embodiments of the invention. Accordingly,the examples should not be construed as limiting the scope of theembodiments of the invention.

As mentioned, there remains a need for a new and improved pedicle screwassembly capable of overcoming the limitations of the conventionaldesigns thereby providing the surgeon with improved intra-operativeflexibility and the patient with an improved prognosis for better andcomplete rehabilitation. The embodiments of the invention address thisneed by providing an improved biased angle polyaxial pedicle screwdevice and method of assembly capable of offering a surgeon more lateralcorrective distance than conventional screw assemblies and accommodatingthe cervical spine anatomy with a biased angle configuration. Referringnow to the drawings and more particularly to FIGS. 1 through 10 wheresimilar reference characters denote corresponding features consistentlythroughout the figures, there are shown preferred embodiments of theinvention.

FIG. 1 illustrates the components of the pedicle screw assembly 10according to an embodiment of the invention. The assembly 10 shown inFIG. 1 is for a 1-level spinal fixation construct. The bone screw(fixator component) 20, which may be embodied as a screw, hook, oranchor, is pre-assembled at the factory by snapping the screw head 30into the bone fixator component 20, and then snapping the saddle pin 40into the screw head 30. This allows the screw head 30 to rotate aboutthe center of rotation freely. This sub-assembly is then inserted and“buried” into the spinal anatomy (not shown) as far as the level of thefemale dimples 24 (shown in FIG. 2(A)) on the bone fixator component 20.Once all of the needed components are assembled, the bone fixatorcomponent 20 is inserted in the spinal anatomy (not shown), thelongitudinal member 50, which may be embodied as a rod, bar, plate,etc., is dropped into the screw head 30, and the blocker 60 is used tofixate the construct 10.

The bone fixator component 20 is shown in FIGS. 2(A) through 2(D) (withreference to FIG. 1) with an angled cut on the top socket 23 of theimplant and having a generally rounded bottom surface 26. This cut topallows for the screw head 20 to angulate in one direction more thananother direction to accommodate the needed extreme angles in theposterior cervical spine. The large angled semi-spherical socket 23 atthe top of the bone fixator component 20 acts as the pivot point for thescrew head 30. This socket 23 is undercut to accommodate a snap fit inassembly and to prevent unintentional disassembly. The socket 23includes an inner portion 21 and an outer portion 25, which comprisesdimples (or cuts) 24. The female spherical cuts 24 are configured so asto be used by a screwdriver (not shown) to insert the bone fixatorcomponent 20 into the patient's spine (not shown).

The screw head 30 is shown in FIGS. 3(A) through 3(D) (with reference toFIGS. 1 through 2(D)). At the bottom 139 of the screw head 30 is a malespherical ball 31 that is slotted 32 for assembly purposes and forexpansion in the final locking of the construct 10. The male sphericalsurface 31 can be treated with a rough media to create a rough textureto encourage galling with the inner portion 21 of the large femalespherical socket 23 in the bone fixator component 20 (of FIGS. 2(A)through 2(D)). In one embodiment of the invention, there may be atapered hole 38 inside the male spherical section 31 of the screw head30 to encourage expansion by the saddle pin 40 (of FIG. 1) as it isdriven into its final locking position. The screw head 30 furtherincludes a pair of opposed upright ends 34, 35 separated by a generallyU-shaped slotted section 36 adapted to receive the longitudinal member50. Preferably, the inner wall 134 of the upright ends 34, 35 includethreads 37. The indent features 39 on the outside 135 of the screw head30 are for various instruments (not shown) to manipulate the screw head30 during surgery.

The saddle pin 40 is illustrated in FIGS. 4(A) through 4(E) (withreference to FIGS. 1 through 3(D)). The saddle pin 40 desirably has agenerally rounded upper portion 42 with a generally sloping uppersurface 46 on top to allow the use of different size longitudinalmembers 50 (of FIG. 1) within the same assembly system 10. The uppersurface 46 includes a slot 43 that extends down to the lower portion 47of the saddle pin 40 to accommodate flexibility in the upper portion 42of the saddle pin 40. The tapered section 41 towards the bottom 47 ofthe saddle pin 40 can be used to expand and “wedge” the slotted malespherical section 31 of the screw head 30 into the bone fixatorcomponent 20 (further shown in FIGS. 8(A) through 8(E)). The bottom tip48 of the saddle pin 40 can be rounded, flat, or pointed to “dig” in thebone fixator component 20 providing another method of locking theconstruct other than the wedging effect described above. The two smallears 44, 45 on top of the saddle pin 40 may be used to orient the saddlepin 40 to always accept a longitudinal member 50 within the screw head30.

FIGS. 5(A) and 5(B) (with reference to FIGS. 1 through 4(E)) illustratethe blocker 60, which is used to push down on the longitudinal member 50(of FIG. 1) that pushes down onto the saddle pin 40 effectively lockingthe construct 10. The threads 61 on the blocker 60 are preferablyconfigured around an outer cylindrical perimeter 63 of the blocker 60,and are preferably standard flat buttress threads that are configured tomate with the threads 37 of the screw head 30. Preferably, as shown inFIG. 5(B), the thread angle, θ, equals 45° and (p equals 90°. The flattype “A” buttress threads 61 of the blocker 60 helps prevent the screwhead 30 from splaying during final tightening (best seen in FIGS. 8(A)through 8(E)). Preferably, the blocker 60 includes an appropriatelysized hex aperture 62 for torque application.

The various angulations scenarios of the fully-assembled screw assembly10 are shown in FIGS. 6(A) through 7(B). The medial angulation shown inFIGS. 6(A) and 6(B) show an unequal angulation. The medial angulation ofthe screw head 30 shown in FIG. 7(A) is equal to the medial angulationof the screw head 30 shown in FIG. 7(B). For example, if a system is toaccommodate a 60 degree angulation all around the center axis of thebone fixator component 20, it would be a very weak system. When used inthe upper thoracic and lower cervical spine, the severe angulation isonly needed in the superior inferior direction pointing towards apatient's head (not shown). FIGS. 6(C) and 6(D) illustrate variousapplications of the screw assembly 10 provided by the embodiments of theinvention. As shown, the screw assembly 10 is configured to haveflexibility in its design (i.e., angulation).

FIGS. 8(A) through 8(E) illustrate cross-sectional views of the assembly10. The saddle pin 40 cannot escape, fall out or vibrate out ofposition, and is always oriented to accept a longitudinal member 50. Itis shown in FIG. 8(A) that the taper 41 towards the bottom of the saddlepin 40 is not engaging the corresponding taper on the screw head 30,thus allowing the screw head 30 to move freely. As shown in FIG. 8(B),the longitudinal member 50 is then dropped into the screw head 30 andrests on the saddle pin 40. At this point the saddle pin 40 is ready todeform to accept a larger size longitudinal member 50 than the slot 43on top of the saddle pin 40 seems to accommodate.

Next, as illustrated in FIG. 8(C), the blocker 60 is inserted into thescrew head 30 preventing the longitudinal member 50 from escaping. Theblocker 60 is now ready to apply downward forces on the saddle pin 40through the longitudinal member 50. As shown in FIG. 8(D), the blocker60 is fully tightened to a predetermined torque. The saddle pin 40 isdriven into the bone fixator component 20 while expanding the bulbousend 31 of the screw head 30. The bulbous end 31 of the screw head 30 hasvery little room to expand. The wedging effect starts to lock theconstruct 10. FIG. 8(E) illustrates the assembly 10 in the lockedposition, whereby the saddle pin 40 has penetrated the bone fixatorcomponent 20 and “lifted” the male spherical portion 31 of the screwhead 30 wedging it further into the socket 23 of the bone fixatorcomponent 20.

In terms of manufacturing the assembly 10, FIGS. 9(A) through 9(D)illustrate various sectional views of the assembly 10 and thecorresponding forces acting upon the various components of the assembly10 during the assembling process. Generally, the assembly 10 locksbecause of the engagement between the socket 23 of the bone fixatorcomponent 20 and the bulbous end 31 of screw head 30 from the forcetransmitted by the saddle pin 40 through the blocker 60 and thelongitudinal member 50. The engaging system generally includes threestages: (1) before engaging (FIG. 9(A)); (2) start to engage (FIG.9(B)); (3) fully engaged (FIGS. 9(C) and 9(D)). The performance of eachcomponent (bone fixator component 20, screw head 30, and saddle pin 50)varies per stage. As shown in FIG. 9(A) (before engaging), the saddlepin 40 has yet to transmit forces to the screw head 30 or to the bonefixator component 20. The saddle pin 40 sits in region R (denoted by theelliptical circles). In this stage, the saddle pin 40 has one directionof limited freedom, vertical.

As shown in FIG. 9(B), the saddle pin 40 starts to engage the bone screw20. Force A is transmitted by the longitudinal member 50 and to thesaddle pin 40 forcing the area of contact to increase accordingly.Enough contact force is generated to bend (denoted by force B) the malesphere 31 of the screw head 30. At this stage, the saddle pin 40 beginsto contact the female socket 23 of the bone fixator component 20. Asshown in FIG. 9(C), the saddle pin 40 is fully engaged. The blocker 60pushes downward against the longitudinal member 50 and the saddle pin 40and creates a force A. Force A is then separated into three forces: C,B, and D₃. Forces D₃ are pushing against the female socket 23 of thebone fixator component 20 thereby creating force E and driving the screwhead 30 upward. By the screw head 30 moving upward, force D₁ is created.Finally, the locking mechanism is completed when forces D₁, D₂, and D₃create a wedge between the screw head 30 and the bone fixator component20 by working against forces C and E.

Since the major engaging component is executed by the forces D₁ and D₃,the above-described engaging method could be substituted by thefollowing: bending forces B and the expansion forces C are ignored orremoved. The forces D₂ are removed since the forces B and C are ignoredor removed. Then, the contact forces D₃ are increased at the tip 48 ofthe saddle pin 40 and the forces D₁ acting on the opening of the bonefixator component 20. As such, FIG. 9(D) illustrates an alternativepossibility of engaging the assembly 10. In this case, the force A istransmitting to the bone fixator component 20 and thereby creating thereaction forces D₃ or K, and depends on the shape of the tip 48 of thesaddle pin 40. Again, forces D₃ or K are pushing against the femalesocket 23 of the bone fixator component 20, creating force E, anddriving the screw head 30 upward. By the screw head 30 moving upward,force D₁ is created. Finally, the locking mechanism is completed whenforces D₁ and D₃ (or K) created a wedge between the screw head 30 andthe bone fixator component 20 by working against forces E.

FIG. 10 (with reference to the components provided in FIGS. 1 through9(D)) is a flow diagram illustrating a method of assembling a pediclescrew assembly 10, wherein the method preferably comprises attaching(100) a screw head 30 comprising a bulbous end 31 to a bone fixatorcomponent 20, wherein the bone fixator component 20 comprises an angledconcave socket 23 adapted to receive the bulbous end 31 of the screwhead 30; securing (102) the bone fixator component 20 in a bone;securing (104) a locking pin 40 in the screw head 30; engaging (106) thesaddle pin 40 with the bone fixator component 20; inserting (108) alongitudinal member 50 in the screw head 30; and inserting (110) ablocker 60 in the screw head 30, wherein engagement of the blocker 60with the screw head 30 causes expansion of the bulbous end 31 of thescrew head 30 in the angled concave socket 23 of the bone fixatorcomponent 20.

Generally, as illustrated in FIGS. 1 through 5(B), the embodiments ofthe invention provide a pedicle screw assembly 10 comprising a screwhead 30 comprising a bulbous end 31; a bone fixator component 20comprising an angled top concave socket 23 adapted to receive thebulbous end 31 of the screw head 30; a pin 40 mounted in the screw head30; and a blocker 60 adapted to engage the screw head 30. The screw head30 comprises a slot 36 adapted to receive a longitudinal member 50.Moreover, the concave socket 23 of the bone fixator component 20comprises a rounded bottom 26. Preferably, the concave socket 23 of thebone fixator component 20 comprises an inner portion 21 adapted toreceive the bulbous end 31 of the screw head 30; and a dimpled 24 outerportion 25.

Additionally, the pin 40 is preferably adapted to engage the bonefixator component 20 and the longitudinal member 50, and the blocker 60is preferably adapted to secure the longitudinal member 50. Preferably,the pin 40 comprises an upper saddle portion 42 having a slot 43 and apair of upright ends 44, 45; and a lower tapered portion 47 adjacent tothe slot 43. Preferably, the screw head 30 further comprises two opposedupright ends 34, 35 separated by the slot 36, wherein each of theopposed upright ends 34, 35 comprise an inner wall 134 and an outer wall135, wherein the inner wall 134 comprises wall threads 37, and whereinthe outer wall 135 comprises grooves 39.

Moreover, the blocker 60 preferably comprises blocker threads 61configured around an outer perimeter 63 of the blocker 60, the blockerthreads 61 being dimensioned and configured to mate with the wallthreads 37 of the screw head 30. Furthermore, the bulbous end 31 of thescrew head 30 may comprise a plurality of slots 32 terminating at anopening 138 at the tip 139 of the bulbous end 31. Also, the bulbous end31 of the screw head 30 preferably comprises a hole 38 configured toreceive the pin 40.

The embodiments of the invention offer a surgeon more lateral correctivedistance than conventional screw assemblies and can accommodate thecervical spine anatomy with a biased angle. The embodiments of theinvention may also be used as a fixation device in the posteriorcervical-thoracic spine.

Additionally, the embodiments of the invention provide an improvement inthe field of surgical lumbar and thoracic and cervical spine treatment.The assembly 10 provided by the embodiments of the invention may also beused anteriorly or posteriorly. Furthermore, the assembly 10 provided bythe embodiments of the invention may be utilized in surgeries to achieveanterior lumbar interbody fusion, posterior lumbar interbody fusion,transverse lumbar interbody fusion, degenerative disc disease, adult andpediatric scoliosis as a fixation device, and posterior cervical fusion.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the invention that others can, by applyingcurrent knowledge, readily modify and/or adapt for various applicationssuch specific embodiments without departing from the generic concept,and, therefore, such adaptations and modifications should and areintended to be comprehended within the meaning and range of equivalentsof the disclosed embodiments. It is to be understood that thephraseology or terminology employed herein is for the purpose ofdescription and not of limitation. Therefore, while the embodiments ofthe invention have been described in terms of preferred embodiments,those skilled in the art will recognize that the embodiments of theinvention can be practiced with modification within the spirit and scopeof the appended claims.

1. A pedicle screw assembly comprising: a screw head comprising abulbous end; a bone fixator component comprising an angled concavesocket adapted to receive said bulbous end of said screw head; a pinmounted in said screw head; and a blocker adapted to engage said screwhead.
 2. The assembly of claim 1, wherein said screw head comprises aslot adapted to receive a longitudinal member.
 3. The assembly of claim1, wherein said concave socket comprises an angled top and a roundedbottom.
 4. The assembly of claim 3, wherein said concave socket of saidbone fixator component comprises: an inner portion adapted to receivesaid bulbous end of said screw head; and a dimpled outer portion.
 5. Theassembly of claim 2, wherein said pin is adapted to engage said bonefixator component and said longitudinal member.
 6. The assembly of claim2, wherein said blocker is adapted to secure said longitudinal member.7. The assembly of claim 1, wherein said pin comprises: an upper saddleportion having a slot and a pair of upright ends; and a lower taperedportion adjacent to said slot.
 8. The assembly of claim 2, wherein saidscrew head further comprises two opposed upright ends separated by saidslot.
 9. The assembly of claim 8, wherein each of said opposed uprightends comprise an inner wall and an outer wall, wherein said inner wallcomprises wall threads, and wherein said outer wall comprises grooves.10. The assembly of claim 9, wherein said blocker comprises blockerthreads configured around an outer perimeter of said blocker, saidblocker threads being dimensioned and configured to mate with said wallthreads.
 11. The assembly of claim 1, wherein said bulbous end of saidscrew head comprises a plurality of slots terminating at an opening at atip of said bulbous end.
 12. The assembly of claim 1, wherein saidbulbous end of said screw head comprises a hole configured to receivesaid pin.
 13. The assembly of claim 1, wherein said bone fixatorcomponent comprises any of a bone screw and a hook.
 14. A pedicle screwassembly comprising: a longitudinal member; a screw head comprising abulbous end, wherein said screw head has a slot adapted to receive saidlongitudinal member; a bone fixator component comprising a concavesocket having a biased angled top and a rounded bottom adapted toreceive said screw head; a locking pin adapted to engage said screwhead, said bone fixator component, and said longitudinal member; and ablocker adapted to engage said screw head and to secure saidlongitudinal member.
 15. The assembly of claim 14, wherein said concavesocket of said bone fixator component comprises: an inner portionadapted to receive said bulbous end of said screw head; and a dimpledouter portion.
 16. The assembly of claim 14, wherein said locking pincomprises: an upper saddle portion having a slot and a pair of uprightends; and a lower tapered portion adjacent to said slot.
 17. Theassembly of claim 14, wherein said bulbous end of said screw headcomprises a hole configured to receive said pin.
 18. The assembly ofclaim 14, wherein said bone fixator component comprises any of a bonescrew and a hook.
 19. A method of assembling a pedicle screw assembly,said method comprising: attaching a screw head comprising a bulbous endto a bone fixator component, wherein said bone fixator componentcomprises an angled concave socket adapted to receive said bulbous endof said screw head; securing said bone fixator component in a bone;securing a locking pin in said screw head; engaging said saddle pin withsaid bone fixator component; inserting a longitudinal member in saidscrew head; and inserting a blocker in said screw head.
 20. The methodof claim 19, wherein engagement of said blocker with said screw headcauses expansion of said bulbous end of said screw head in said angledconcave socket of said bone fixator component.